Make heapprofd work with MLS.

Arbitrary apps need to connect to heapprofd in order to send samples.

Relevant denial trying to profile com.google.android.inputmethod.latin
on userdebug:

12-20 14:50:20.420 25219 25219 I heapprofd: type=1400 audit(0.0:1006): avc: denied { read } for path="/proc/24819/mem" dev="proc" ino=244219 scontext=u:r:heapprofd:s0 tcontext=u:r:untrusted_app_27:s0:c133,c256,c512,c768 tclass=file permissive=1

Bug: 121370989

Test: m
Test: flash walleye
Test: profile com.google.android.inputmethod.latin

Change-Id: Iee82c8c49951e5a5726cd5ab0b9e8fa71226c802